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Hormones Flashcards

1
Q

Compare and contrast the communication methods of the endocrine and nervous systems.

A

The endocrine system communicates via hormones, many of which act as long-distance chemical signals. The nervous system communicates via long-distance electrical signals and short-distance chemical signals.

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2
Q

What is a hormone?

A

A hormone is a chemical signal that is secreted into the circulatory system and communicates regulatory messages within the body. Hormones may reach all parts of the body but only certain types of cells–the “target” cells–are equipped to respond.

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3
Q

What is neuroendocrine signaling?

A

In neuroendocrine signaling, specialized neurons–called neurosecretory cells–secrete neurohormones that enter the bloodstream and trigger responses in target cells anywhere in the body.

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4
Q

What are pheromones?

A

Pheromones are small molecules released into the external environment, and function in the communication between members of the same species. Pheromone signaling is NOT an example of endocrine signaling.

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5
Q

In cell signaling, what are the types of local regulators (signals involved over short distances, such as in paracrine and autocrine signaling)?

A
  1. Modified fatty acids such as prostaglandins.
  2. Polypeptides such as cytokines and growth factors.
  3. Amines such as serotonin.
  4. Gases such as nitric oxide.
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6
Q

What are the types of hormones?

A
  1. Polypeptides such as insulin.
  2. Cholesterol-derived steroids such as cortisol.
  3. Amines (modified amino acids) such as epinephrine and thyroxine.
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7
Q

Name some examples of hydrophilic cell signals.

A

Polypeptides and epinephrine,

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8
Q

Name some examples of hydrophobic cell signals.

A

Steroids such as cortisol and the sex hormones and thyroid hormones.

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9
Q

How do water-soluble hormones work?

A

They are secreted by exocytosis, travel in the blood, bind to cell surface receptors on target cells, and induce changes in cellular responses and/or gene transcription.

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10
Q

How do lipid-soluble hormones work?

A

They diffuse out of the endocrine cell, bind transport proteins that keep them soluble in the blood, diffuse into the target cells and bind to receptors in the cytoplasm or nucleus, and induce changes in gene transcription.

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11
Q

How does the hormone estradiol work?

A

Estradiol is a lipid-soluble hormone. It goes into the reproductive organs of the female and crosses directly into the cytosol to bind to an intracellular receptor. Then, it activates gene expression on the vitellogenin gene.

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12
Q

Do water-soluble or lipid-soluble hormones work faster to achieve a cellular response?

A

Even though there are fewer intermediate steps for a lipid-soluble hormone, a water-soluble hormone works faster. A lipid-soluble hormone must activate transcription machinery while in the water-soluble hormone system, the machinery is already present and can activate the cellular response faster.

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13
Q

How does the body respond to a high stress situation?

A

The adrenal medulla (an endocrine gland) secretes epinephrine that enters the bloodstream. It enters the liver, where it binds to a B receptor on a liver cell. This activates a signal transduction pathway that involves adenylyl cyclase and protein kinase A, leading to the secretion of glucose into the blood.

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14
Q

What happens when epinephrine binds to a B receptor on a smooth muscle cell?

A

Adenylyl cyclase is activated, which then activates protein kinase A. The cellular response is the relaxation of the cell. This allows more blood to flow to skeletal muscle cells.

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15
Q

How does the cellular response change based on what type of cell epinephrine binds?

A

When epinephrine binds to B receptors on liver and smooth muscle cells, the response is different. In the liver cell, the end result is the release of glucose into the bloodstream. In the smooth muscle cells, the end result is vasodilation and increased blood flow.

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16
Q

What happens when epinephrine binds to smooth muscle cells with an a receptor?

A

The receptor activates phospholipase C, which activates the second messengers of IP3, calcium, calmodulin, etc. This causes the cell to contract, giving it less blood.

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17
Q

Why does epinephrine bind to smooth muscle cells with an a receptor?

A

When epinephrine binds to smooth muscle cells with B receptors, the end result is vasodilation. This causes an inequality of blood flow in the skeletal muscles. To end this effect, it must bind to cells with a receptors in the intestines in order to decrease blood flow and vasodilation.

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18
Q

What is the difference between liver cells and smooth muscle cells with B receptors that epinephrine binds to?

A

The difference is in the types of proteins protein kinase A activates in the cascade.

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19
Q

What is a simple endocrine pathway?

A

There is a single hormone released that stimulates a direct response.

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20
Q

What has to happen to the contents of the stomach as they move into the intestine?

A

The pH of the stomach is about 1 to 2 (highly acidic), and the pH of the intestine is neutral, about 7. Therefore, the contents of the stomach need to be neutralized before moving to the intestine.

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21
Q

What is the duodenum?

A

The very beginning of the small intestine. This is where the S cells are found.

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22
Q

What happens in the duodenum when the pH drops?

A

A sensor in the S cells of the duodenum activates, causing the cells to secrete a hormone called secretin.

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23
Q

What does secretin do in the secretin signaling pathway?

A

After secretion by the S cells, it travels through the blood and is recognized by specific cells in the pancreas.

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24
Q

How does the pancreas react to the hormone secretin?

A

It releases bicarbonate that raises the pH in the duodenum and neutralizes the acid.

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25
What happens as the pH in the duodenum rises?
The stimulus to the endocrine cells in the duodenum decreases. This causes them to slow down and eventually stop the release of bicarbonate. This is an example of a negative feedback system.
26
Describe the initial response in a mother with a feeding baby.
The baby stimulates a nervous response on the breast which sends a signal to the hypothalamus.
27
What does the hypothalamus do in response to stimulation (milk example)?
The hypothalamus produces oxytocin and sends it to the posterior pituitary. Then it enters the bloodstream until it reaches the smooth muscle in the mammary glands.
28
What effect does oxytocin have on the mammary glands?
It tells the smooth muscle of the mammary glands to contract. This causes the milk to squeeze out so that the baby can drink.
29
Why is the neuroendocrine pathway of milk release in a mother an example of a positive feedback system?
As the baby drinks, it continues to stimulate the breast. This maintains the signals to the hypothalamus, causing milk to be released until the baby stops drinking. Then, the release of oxytocin is halted.
30
What is a hormone cascade pathway?
This is a type of signaling in which one hormone causes the release of another hormone, which eventually leads to a response. There can be any number of intermediate hormone responses in the cascade
31
What is another name for thyroid hormone?
Thyroxine.
32
What is the role of thyroid hormone?
It increases the metabolism.
33
How does the thyroid hormone cascade pathway begin?
The stimulus is the drop in thyroid hormone level. The hypothalamus then releases thyrotropin-releasing hormone (TRH) into the bloodstream, where it travels to the anterior pituitary.
34
When TRH reaches the anterior pituitary, what happens?
The anterior pituitary releases another hormone called thyroid stimulating hormone (TSH). TSH enters the bloodstream and travels until it reaches the thyroid gland.
35
What happens when TSH reaches the thyroid gland?
The thyroid gland has receptors for TSH. The gland releases thyroid hormone, which enters the bloodstream until it meets its target cells and initiates a cellular response.
36
What are the three hormones involved in the thyroid hormone cascade pathway?
1. TRH from the hypothalamus 2. TSH from the anterior pituitary 3. Thyroid hormone from the thyroid.
37
What happens as the level of thyroid hormone increases?
This sends a negative feedback signal to the hypothalamus and to the anterior pituitary to communicate the message that there is enough thyroid hormone and to slow down the process.
38
Are negative or positive feedback regulation systems more common? Why?
Negative. Hormone pathways involved in homeostasis typically involve negative feedback in order to maintain the pre-existing state.
39
How does the molting of the exoskeleton in an insect begin?
Neurosecretory cells in the corpora cardiaca (a nerve in the brain) release PTTH, which travels to the thoracic gland.
40
What happens in the thoracic gland when PTTH reaches it?
The thoracic gland releases ecdysteroid, which tells the insect to molt.
41
What hormone does the corpora allata (a nerve in the brain) release? Why?
Juvenile hormone (JH) This hormone determines what stage of molting an insect will undergo, whether from early larva to later larva to pupa to adult.
42
What happens when there is ecdysteroid and high levels of JH in an insect?
There is a transition from one type of larva to another. The insect stays in the same life stage.
43
What happens when there is ecdysteroid and low levels of JH in an insect?
There is a transition from larva to pupa.
44
What happens when there is ecdysteroid and no JH in an insect?
There is a transition from pupa to adult (butterfly/moth).
45
What example was given to illustrate the fact that the nervous and endocrine systems can coordinate responses?
The pairing of ecdysteroid and juvenile hormone in the life stages of butterflies and moths.
46
What are the ways in which hormonal signals can be terminated?
1. Intracellular termination of the hormone by degradation of inhibition of transduction. 2. Extracellular degradation by the liver, spleen, blood, lymph, etc. 3. Removal of the hormone by excretion via the kidneys.
47
How long does epinephrine typically last in the body?
One to three minutes before being broken down.
48
How long does cortisol typically last in the body?
Cortisol is involved in long-term stress response, so it stays in the bloodstream for one to three days.
49
What are endocrine cells?
Cells that are dispersed in organs that are part of other organ systems. An example would be the S cells of the duodenum.
50
What are endocrine glands?
An aggregation of endocrine cells; ductless organs that secrete hormones into the surrounding fluid. (examples are the hypothalamus and pituitary gland)
51
What are exocrine glands?
Exocrine glands (such as the salivary glands) secrete substances into the cavities of the surface of the body using a duct.
52
What are tropic hormones?
Hormones that have an endocrine gland or endocrine cell as the target.
53
What are non-tropic hormones?
Hormones that directly influence non-endocrine cells. (some hormones are both tropic and non-tropic)
54
What hormone(s) does the pineal gland release?
Melatonin.
55
What hormone(s) does the hypothalamus release?
1. Hormones released from posterior pituitary (oxytocin and vasopressin) 2. Releasing and inhibiting hormones.
56
What hormone(s) does the anterior pituitary release?
1. Follicle-stimulating hormone (FSH) 2. Luteinizing hormone (LH) 3. Thyroid-stimulating hormone (TSH) 4. Adrenocorticotropic hormone (ACTH) 5. Prolactin 6. Growth hormone (GH)
57
What hormone(s) does the posterior pituitary release?
1. Oxytocin 2. Vasopressin (antidiuretic hormone [ADH])
58
What hormone(s) does the thyroid gland release?
1. Thyroid hormone (T3 and T4) 2. Calcitonin
59
What hormone(s) does the parathyroid glands release?
Parathyroid hormone (PTH)
60
What hormone(s) does the adrenal medulla release?
1. Epinephrine 2. Norepinephrine
61
What hormone(s) does the adrenal cortex release?
1. Glucocorticoids 2. Mineralocorticoids
62
What hormone(s) does the pancreas release?
1. Insulin 2. Glucagon
63
What hormone(s) do the ovaries release?
1. Estrogens 2. Progestins
64
What hormone(s) do the testes release?
Androgens
65
What is the role of the hormone melatonin?
It participates in regulation of biological rhythms.
66
What is the role of releasing and inhibiting hormones?
Regulation of anterior pituitary.
67
What is the role of FSH?
Follicle-stimulating hormone stimulates the ovaries and testes.
68
What is the role of LH?
Luteinizing hormone stimulates the ovaries and testes.
69
What is the role of TSH?
Thyroid-stimulating hormone stimulates the thyroid gland.
70
What is the role of ACTH?
Adrenocorticotropic hormone stimulates the adrenal cortex.
71
What is the role of the hormone prolactin?
It stimulates mammary gland cells.
72
What is the role of GH?
Growth hormone stimulates growth and metabolic functions.
73
What is the role of the hormone oxytocin?
1. Regulates milk secretion by the mammary glands. 2. Stimulates contraction of smooth muscle cells in the uterus (during birthing) and mammary glands. 3. Influences maternal behaviors.
74
What is the role of the hormone vasopressin?
It promotes retention of water by the kidneys; influences social behavior and bonding.
75
What is the role of thyroid hormone?
It stimulates and maintains metabolic processes.
76
What is the role of the hormone calcitonin?
It lowers blood calcium level.
77
What is the role of PTH?
Parathyroid hormone raises blood calcium level.
78
What is the role of the hormone epinephrine?
It raises blood glucose level; increases metabolic activities; constricts certain blood vessels.
79
What is the role of the hormone norepinephrine?
It raises blood glucose level; increases metabolic activities; constricts certain blood vessels.
80
What is the role of the hormone glucocorticoids?
They raise blood glucose levels.
81
What is the role of the hormone mineralocorticoids?
They promote reabsorption of Na+ and excretion of K+ in kidneys.
82
What is the role of the hormone insulin?
It lowers blood glucose level.
83
What is the role of the hormone glucagon?
It raises blood glucose level.
84
What is the role of the hormone estrogen?
It stimulates uterine lining growth and promotes development and maintenance of female secondary sex characteristics.
85
What is the role of the hormone progestin?
It promotes uterine lining growth.
86
What is the role of androgens?
They support sperm formation and promote development and maintenance of male secondary sex characteristics.
87
Where is the pituitary gland located?
The pituitary gland is fused to the base of the hypothalamus (an extension of it) at the bottom of the brain.
88
Where is the pineal gland located?
The brain.
89
Where are the thyroid and parathyroid glands located?
The neck.
90
Where are the adrenal glands located?
Above the kidneys.
91
In vertebrates, coordination of endocrine signaling relies heavily on what gland?
The hypothalamus.
92
How does the hypothalamus coordinate endocrine signaling?
The hypothalamus is a neurosecretory gland located in the brain. It receives information from nerves throughout the body and then initiates endocrine signaling appropriate for those conditions. Hormonal signals from the hypothalamus travel to the pituitary, which is located at its base.
93
How does the hypothalamus communicate with the posterior pituitary?
Axons from the hypothalamus reach into the posterior pituitary and secrete neurohormones synthesized in the hypothalamus. So any hormone released from the posterior pituitary was made in the hypothalamus.
94
What is the anterior pituitary?
An endocrine gland that secretes hormones in response to hypothalamic hormones.
95
How does the hypothalamus communicate with the anterior pituitary?
The hypothalamus secretes a "releasing hormone" or an "inhibiting hormone." This hypothalamic hormone reaches the anterior pituitary via the blood. The anterior pituitary then releases a hormone or stops releasing a hormone.
96
What happens when the osmolarity of the blood increases? (such as after sweating profusely)
The concentration of solutes in the blood is high. This sends a signal to the hypothalamus, which sends signals to other parts of the brain to make the feeling of thirst.
97
What hormone does the hypothalamus release in response to high osmolarity of the blood?
Osmoreceptors in the hypothalamus trigger the release of ADH (antidiuretic hormone). It sends ADH to the posterior pituitary, which then releases it into the blood.
98
What happens to ADH after secretion by the pituitary gland?
It enters the bloodstream until it reaches the kidneys.
99
How do the kidneys respond to ADH?
They send water back into the bloodstream to bring the osmolarity of the blood back down.
100
What is the normal range for blood osmolarity?
275-295 mOsm/L.
101
Give an example of a hypothalamic hormone that is a releasing hormone for the anterior pituitary.
Hypothalamic prolactin-releasing hormone (TRH can also do this) stimulates the anterior pituitary to secrete prolactin, which stimulates milk production.
102
Which hormones produced by the anterior pituitary have tropic effects only?
1. FSH 2. LH 3. TSH 4. ACTH
103
Which hormones produced by the anterior pituitary have non-tropic effects only?
1. Prolactin 2. MSH
104
Which hormones produced by the anterior pituitary have tropic and non-tropic effects?
GH
105
What is the liver's response to growth hormone?
The liver releases insulin-like growth factors that stimulates bone and cartilage growth. This is a tropic effect.
106
What are adipocytes' response to growth hormone?
Adipocytes respond by breaking down triglycerides. This is a non-tropic effect.
107
What causes gigantism?
Too much growth hormone during development.
108
What causes pituitary dwarfism?
Too little growth hormone during development.
109
What causes acromegaly?
Too much growth hormone during adulthood.
110
What are the two forms of thyroid hormone?
T3 is most active. T4 can be converted to T3. The number after T is the number of iodine atoms.
111
What is hypothyroidism, and what are the symptoms?
Hypothyroidism occurs when there is too little thyroid function. It leads to weight gain, lethargy, and cold intolerance.
112
What is hyperthyroidism, and what are the symptoms?
Hyperthyroidism occurs when there is too much thyroid hormone. It leads to high body temperature, sweating, weight loss, irritability, and high blood pressure.
113
What causes goiter?
Lack of iodine impedes production of active T3 and T4, which induces overproduction of TSH, and results in goiter and other problems. Goiter is the inflammation of the thyroid.
114
What causes cretinism?
In development, thyroid hormone deficiency leads to delayed skeletal growth and poor mental development, called cretinism.
115
What is Graves' disease?
This is a thyroid disease caused by antibodies that stimulate the thyroid receptors. Normally, TSH binding to the thyroid stimulates the production of T3 and T4. But with Graves' disease, even in the absence of TSH, those antibodies are able to turn on the receptor for TSH, causing the thyroid to always be "on."
116
Where is the parathyroid located?
The parathyroid is located at small points within the thyroid.
117
What two hormones are involved in modulating calcium levels within the body?
Parathyroid hormone and calcitonin (secreted by the thyroid).
118
How does the body respond to low calcium levels?
When calcium levels fall, a signal is sent to the parathyroid hormone to release parathyroid hormone.
119
What two responses does PTH have?
1. In the kidney, it stimulates the uptake of calcium ions and promotes activation of vitamin D via kidney reabsorption and intestine reabsorption. 2. It signals to the bone to release calcium.
120
How does the body respond to high calcium levels?
Calcitonin is released from the thyroid, lowering calcium levels in the blood by inhibiting bone breakdown and excreting calcium via the kidneys.
121
What is the effect of having too little calcium in the blood?
When calcium is too low, muscles may contract convulsively.
122
What is the effect of having too much calcium in the blood?
When calcium is high, the formation of calcium phosphate can cause organ damage.
123
Describe the structure of the adrenal glands.
Each adrenal gland is divided into two areas: the medulla and the cortex.
124
How do the functions of the adrenal medulla and cortex differ?
The adrenal cortex is important in controlling long-term stress while the adrenal medulla controls short-term stress.
125
What is the difference in the way in which the hypothalamus communicates with the adrenal medulla and cortex?
The hypothalamus communicates with the medulla via neuroendocrine signals. It communicates with the cortex via endocrine signals.
126
How does the hypothalamus initiate a short-term stress response?
The stimulus of physical threat, exercise, or cold exposure causes the hypothalamus to activate the adrenal medulla via nerve impulses. In response, the adrenal medulla secretes epinephrine and norepinephrine.
127
How does the hypothalamus initiate a long-term stress response?
The stimulus of low blood sugar, decreased blood volume and pressure, or shock causes the hypothalamus to activate the adrenal cortex via hormonal signals (ACTH). The adrenal cortex secretes mineralocorticoidss and glucocorticoids in response.
128
What are the effects of mineralocorticoids?
The retention of sodium ions and water by kidneys and increased blood volume and blood pressure.
129
What are the effects of glucocorticoids?
Proteins and fats are broken down and converted to glucose, leading to increased blood glucose, and they cause a partial suppression of the immune system.
130
How does the signaling pathway for the gonads and sex hormones work?
The hypothalamus releases gonadotropin-releasing hormone (GnRH), which travels to the pituitary, causing it to release FSH and LH. In males, these hormones travel to the testes, and in females, they travel to the ovaries. The testes then produce testosterone and the ovaries produce estradiol.
131
What is the negative feedback for the sex signaling pathway in males?
An increase in levels of testosterone triggers a reduction in the amount of GnRH.
132
How does feedback for the sex signaling pathway in females work?
When estradiol levels are low, this feeds back to reduce the levels of GnRH, FSH, and LH. (negative feedback) When estradiol levels are high, this feeds back to increase the levels of GnRH, FSH, and LH. (positive feedback)
133
What two male hormones determine what reproductive structures are formed? How do they do this?
Testosterone and anti-Mullerian hormone (AMH) direct the formation of sperm-carrying ducts and the degeneration of female ducts. In the absence of these hormones, the opposite occurs.
134
What are the effects of synthetic androgens?
They increase muscle mass by enhancing secondary male characteristics, but there are several negative side effects such as impotence, reduced sperm counts, enlarged prostate, development of breasts, headaches, etc.
135
How does the body respond to low blood glucose?
Low glucose levels trigger the secretion of glucagon by alpha cells of the pancreas. Glucagon tells the liver to release glucose into the bloodstream.
136
How does the body respond to high blood glucose?
The glucose from food triggers the secretion of insulin by beta cells of the pancreas. Insulin tells the liver to take up glucose and polymerize it into glycogen. This results in a decrease of glucose in the blood.
137
Describe the characteristics of type 1 diabetes.
1. Autoimmune disorder: immune system destroys the beta cells of the pancreas, leading to insulin insufficiency. 2. 10% of cases. 3. Onset mainly in children. 4. Treat by injecting insulin.
138
Describe the characteristics of type 2 diabetes.
1. Target cells stop responding to insulin. 2. 90% of cases. 3. Onset mainly in overweight adults. 4. Treat by diet and exercise.
139
Which part of the hypothalamus releases melatonin?
Neurons in the suprachiasmatic nucleus of the hypothalamus induce melatonin release at night, which promotes sleep.
140
What inhibits the release of melatonin?
Blue light exposure.
141
What variables shape a hormone's effect on an animal's body and behavior?
1. Concentration of the hormone in the body. 2. Presence of the hormone receptor in a cell. 3. Response of the cell when the receptor binds the hormone.

BSCI 1511 (32 decks)

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